This proposal outlines the continued development of methodology and theory using carbon-13 magnetic resonance important in the study of biomedical problems. Theoretical work largely deals with diffusional motion of biomedical molecules and model systems required to verify the experimental methods. Spectroscopic developments include slowspinning director alignment of nematic solvents to simulate molecular orienting conditions observed in biologically ordered systems such as membranes. Spectroscopic research will use high magnetic fields to determine subtle conformational features associated with optical centers in isoprenoid molecules. Relaxation data on continuous chain alkanes, model polymers, and biomacromolecules is used to characterize molecular motions of the overall and segmental variety. Solid state NMR methods using both cross polarization (CP) and magic angle spinning (MAS) provide relatively high resolution spectra. Applications primarily to nitrogen-containing compounds, heterocycles, nucleosides, nucleic acid, etc., are planned. Subtle interactions which average in liquid samples can be frozen out in microcrystalline powders for study. Finally, work on site specific 2H/1H isotope ratios and their variations depending upon the compounds' chemical history will be pursued. The effect of various biosynthetic pathways will be explored.